Pulleys to facilitate hoisting and lowering of loads and general products are well known. These pulleys are especially used in the building and construction sectors and are normally handled by two persons, one of them being placed at the top where the pulley is fastened and the other at floor level.
This pulley consists of a disk with a supporting groove or race guiding the rope, idling around its shaft supported by a yoke equipped with a fastening device.
These pulleys have no protective device to prevent the load from falling down when the pull leg of the rope is released by the operator at floor level. Some pulleys have been provided with a safety ratchet gear blocking the load and consisting of a gear wheel keyed onto the disk shaft and a ratchet but this safety system has several drawbacks, the most important of which is the fact that this ratchet gear has to be released for each operation and this is extremely dangerous.